USB Type-C connectors include various functions such as USB, Display Port, Thunderbolt (registered trademark), and Power Delivery. Thus, when a Type-C connector is mounted on a small-size computer such as a mobile notebook-type PC or a tablet computer that cannot include many interface (I/F) ports, the Type-C connector can substitute for a Display Port connector, DC-IN connector, and the like.
In the connection between a host device and a peripheral device using a USB Type-C connector, two ports of Super Speed (SS) mode of USB 3.1 standard and one port of USB 2.0 standard are supported. That is, the host device provides two USB 3.1 ports and one USB 2.0 port to the peripheral device.
Here, when a peripheral device including two devices of USB 2.0 standard are connected to the host device, the host device only supports one USB 2.0 port, and thus, for example, a hub controller IC is provided with the peripheral device. By connecting the two USB 2.0 devices to the downstream ports of the hub controller IC of the peripheral device, the host device can control the two USB 2.0 devices via the hub controller IC.
The hub controller IC may have a power saving function that allows the hub controller IC to transit into a power saving state when the entire devices connected to the downstream ports do not operate. However, when the connected USB 2.0 devices operate with different frequency, the period during which the hub controller IC is maintained in the power saving state becomes short, and the effectiveness of the power saving becomes poor.
Thus, a new function to use multiple USB 2.0 port connections while saving the power is required.